In both dental research and clinical practice, how patients perceive the effects of dental interventions is essential, and one standard instrument should exist to measure and compare these effects. Here, oral health- related quality of life (OHRQoL) is the most promising concept. The most widely used OHRQoL instrument for adults, the 49-item Oral Health Impact Profile (OHIP), combines items into 7 scores that putatively measure 7 latent dimensions of perceived oral health. This set of 7 scores has been used for almost 20 years but has never been validated. In fact, recent evidence indicates that the OHIP dimensional structure is not correct, which creates a fundamental measurement problem for the assessment of OHRQoL using OHIP. The major goals of this proposal are (i) to determine which OHRQoL dimensions exist and to derive a new OHIP dimensional structure, (ii) to derive 2 new OHIP short forms and a computer adaptive testing version based on these revised dimensions, and (iii) to validate the revised OHIP dimensional structure and the newly derived versions. Existing OHIP data from 6,628 general-population subjects and 2,502 dental patients from 6 countries will be used both to derive revised OHIP dimensions by applying factor analysis and to test the newly identified dimensions. In addition, 2 new shorter OHIP forms and a computer adaptive testing version (all aimed at reducing self-reporting burden) will be developed using item response theory. Finally, a new sample of 2,000 dental patients in Minnesota will be used to validate the derived OHIP dimensions and new OHIP forms in cross-sectional and longitudinal analyses using other measures of self-reported oral health and clinical oral-health indicators. During the validation process, items from 2 other OHRQoL instruments will be integrated into the instrument to create one standard OHRQoL instrument. A unified framework for OHRQoL assessment based on OHIP will be created, and methodologies such as item response theory and bifactor analysis will ensure that scores from newly derived short-form OHIP versions are compatible with scores from longer OHIPs (score equating). The relationship of OHIP scores to health-related quality of life outcome measures will be explored using methodology from NIH's Patient-Reported Outcomes Measurement Information System (PROMIS). The revised OHIP will measure perceived oral health with a valid set of OHIP dimension scores from instruments with different lengths that will nevertheless be compatible across settings. A profile of sound OHIP dimension scores can become dentistry's standard tool for assessing oral health and treatment effects from the patient's perspective. The revised OHIP will allow effects from all oral interventions to become comparable, aiding dentists and patients in their evaluation of treatment alternatives and informing health care systems for setting resource priorities.